1. Field of the Invention
The present invention relates generally to delivery or transport mechanisms, and more particularly to a delivery device which is capable of delivering articles to be heated within a compound furnace, including at least two furnace chambers differing in heating conditions, wherein the articles are transported from one chamber to another chamber.
2. Description of the Prior Art
With respect to the methods for successively delivering articles to be heated within a heating furnace, there have heretofore generally been adopted a pusher method in accordance with which articles to be heated are successively pushed into a furnace from the rear by means of a pusher cylinder; a pinch roller method in accordance with which the articles to be heated are delivered in a forward direction by pairs of oppositely rotating rollers disposed upon the upper and lower sides, or upon the left and right sides, of the delivery track; a roller method in accordance with which the articles to be heated are delivered by a plurality of rollers, disposed upon the lower face of a furnace and rotating in the same direction; a walking beam method in accordance with which a beam capable of moving in both the vertical and horizontal directions is disposed so as to penetrate a furance from the inlet to the outlet thereof, the beam traversing a rectangular path of movement by initially raising the articles to be heated on the hearth, forwarding the articles by a single pitch or step, lowering the articles upon the hearth at a point forward of the original position by one pitch or step, and returning through the one pitch or step at a level below the hearth; as well as other similar methods.
The pusher method, as a method of delivering articles to be heated within a heating furnace, is defective as the articles to be heated are delivered in a state wherein they are in contact with each other whereby melt adhesion is caused within a high temperature zone. The pinch roller method or roller method are suitable for the delivery of long articles, but are not suitable for the delivery of a large number of small articles of diameters and lengths which do not vary appreciably. The walking beam method is defective in that when the furnace length is long, the delivery within the furnace cannot be assuredly accomplished.
As is seen from the foregoing, each of the conventional methods is defective in some point or another, and by the adoption of a rotary hearth method, it has been possible for the first time to assuredly perform the delivery of the articles to be heated while preventing the articles from coming into contact with each other, and in addition, to assure the precise and stable delivery even when the articles are asymmetric and the deviation of the direction at the furnace outlet, that is, rotation of the articles within the furnace, is not permitted.
In the case of a compound furnace having at least two chambers of different heating conditions, and wherein such rotary hearth furnace is used, such as for example, a high temperature furnace, and is combined with another low temperature furnace for cooling or soaking, when a delivery device to be used exclusively for transporting the articles to be heated from one furnace to the other is assembled in conjunction with this compound furnace, since the furnace temperature is very high, the influence of the high furnace temperature upon the moving parts of the delivery device and the articles to be heated must be taken into consideration.
Adoption of the above-mentioned pusher method as such an exclusive delivery means within the above-mentioned compound furnace has been proposed, however, when the articles to be heated are arranged in a plurality of rows upon the rotary hearth furnace, it is difficult to individually pick up the articles arranged in parallel rows, and when the articles to be heated are relatively small, the articles readily drop into the clearance between the hearth floor of the rotary hearth furnace and the floor of the delivery passage whereby the delivery operation becomes unstable. In addition, as the articles to be heated are directly pushed into the furnace, the pushing force acts upon the articles as a lateral pressure, which adversely affects the articles by causing other undesired phenomena, such as for example, slipping of the articles upon the hearth, to occur.
As a means for overcoming such adverse affects caused by this direct pushing and the resulting slipping, there has also been proposed a method in accordance with which the articles to be heated are received upon a tray. When such a tray is employed however, an additional operation is necessary for charging the articles onto the tray and for removing them therefrom. Accordingly, the apparatus is inevitably complex and the operation becomes intricate.